The Western United States, commonly referred to as the American West or simply "the West," traditionally refers to the region comprising the westernmost states of the United States. Because the U.S. expanded westward after its founding, the meaning of the West has evolved over time. Prior to about 1800, the crest of the Appalachian Mountains was seen as the western frontier. Since then, the frontier moved further west and the Mississippi River was referenced as the easternmost possible boundary of the West.

Besides being a purely geographical designation, "The West" also has anthropological connotations. While this region has its own internal diversity, there is arguably an overall shared history, culture (music, cuisine), mind set or world view and closely interrelated dialects of English. As with any region of such geographically large extent and varied culural histories, many subregions of The American West possess distinguishing and idiosyncratic qualities.

The states from the Rockies westward have something of a dual nature of semiarid steppes and arid deserts in the lowlands and plateaus, and mountains and coniferous forests in the uplands and coastal regions.

The West can be divided into the Pacific States; Alaska, California, Hawaii, Oregon, and Washington, with the term West Coast usually restricted to just California, Oregon, and Washington, and the Mountain States, always Arizona, Colorado, Idaho, Montana, Nevada, New Mexico, Utah, and Wyoming. Alaska and Hawaii, being detached from the other western states, have few similarities with them, but are usually also classified as part of the West. Western Texas in the Chihuahuan Desert is also traditionally considered part of the Western U.S, though from a climatological perspective the West might be said to begin just west of Austin, TX where annual rainfall drops off significantly from what is typically experienced in the East, with a concurrent change in plant and animal species.

It is rare for any state east of the Mississippi River to be considered part of the modern west. Historically, however, the Northwest Territory was an important early territory of the U.S., comprising the modern states of Ohio, Indiana, Illinois, Michigan and Wisconsin, as well as the northeastern part of Minnesota. Also, American sports leagues with a "Western" conference or division often have members east of the Mississippi for various reasons such as not enough true Western teams, not strictly adhering to geographic regions, etc. For example, the NBA and NHL each have a Western Conference with a member in Tennessee.

However, the United States Census Bureau uses only one definition of the West in its reporting system, which may not coincide with what may be historically or culturally considered the West. For example, in the 2000 Census, the Census Bureau included the state with the second largest Hispanic population, Texas, in the South, included the state with the second largest American Indian population, Oklahoma, also in the South, and included the Dakotas, with their large populations of Plains Indians, in with the Midwest. However, it should be noted that the western half of Oklahoma and far West Texas, are usually neither culturally, geographically or socioeconomically identified with the South.

Statistics from the 2000 United States Census, adjusted to include the second tier of States west of the Mississippi, show that, under that definition, the West would have a population of 91,457,662, including 1,611,447 Indians, or 1.8% of the total, and 22,377,288 Hispanics (the majority Mexican), or 24.5% of the total. Indians comprise 0.9% of all Americans, and Hispanics, 12.5%. Asians, important from the very beginning in the history of the West, totaled 5,161,446, or 5.6%, with most living in the Far West. African-Americans, totaled 5,929,968, or 6.5%—lower than the national proportion (12.8%). The highest concentrations (12%) of black residents in the West are found in Texas—which is also considered a Southern state—and in California.

The West is still one of the most sparsely settled areas in the United States with 49.5 inhabitants per square mile (19/km²). Only Texas with 78.0 inhabitants/sq mi. (30/km²), Washington with 86.0 inhabitants/sq mi. (33/km²), and California with 213.4 inhabitants/sq mi. (82/km²) exceed the national average of 77.98 inhabitants/sq mi. (30/km²).

These maps from the 2000 US Census highlight differences from state to state of three minority groups. Note that most of the Native American, Hispanic, and Asian population is in the West.

The entire Western region has also been strongly influenced by European, Native and Hispanic culture; it contains the largest number of minorities in the U.S. and encompasses the only four American states where all racial groups including Caucasians are a minority (California, Hawaii, New Mexico, and Texas). While most of the studies of racial dynamics in America such as riots in Los Angeles have been written about European and African Americans, in many cities in the West and California, European and African Americans together are less than half the population because of the preference for the region by Hispanics and Asians. African and European Americans, however, continue to wield a stronger political influence because of the lower rates of citizenship and voting among Asians and Hispanics.

The Western United States has a higher sex ratio (more males than females) than any other region in the United States.[3]

Beyond the valleys lie the Sierra Nevada in the south and the Cascade Range in the north. Mount Whitney, at 14,505 feet (4,421 m) the tallest peak in the contiguous 48 states, is in the Sierra Nevada. The Cascades are also volcanic. Mount Rainier, a volcano in Washington, is also over 14,000 feet (4,300 m). Mount St. Helens, a volcano in the Cascades erupted explosively in 1980. A major volcanic eruption at Mount Mazama around 4860 BCE formed Crater Lake. These mountain ranges see heavy precipitation, capturing most of the moisture that remains after the Coast Ranges, and creating a rain shadow to the east forming vast stretches of arid land. These dry areas encompass much of Nevada, Utah and Arizona. The Mojave Desert and Sonoran Desert along with other deserts are found here.

Beyond the deserts lie the Rocky Mountains. In the north, they run almost immediately east of the Cascade Range, so that the desert region is only a few miles wide by the time one reaches the Canadian border. The Rockies are hundreds of miles wide, and run uninterrupted from New Mexico to Alaska. The Rocky Mountain Region is the highest overall area of the United States, with an average elevation of above 4,000 feet. The tallest peaks of the Rockies, 54 of which are over 14,000 feet (4,250 meters approx.), are found in central and western Colorado.

The West has several long rivers that empty into the Pacific Ocean, while the eastern rivers run into the Gulf of Mexico. The Mississippi River forms the easternmost possible boundary for the West today. The Missouri River, a tributary of the Mississippi, flows from its headwaters in the Rocky Mountains eastward across the Great Plains, a vast grassy plateau, before sloping gradually down to the forests and hence to the Mississippi. The Colorado River snakes through the Mountain states, at one point forming the Grand Canyon. The Colorado is a major source of water in the Southwest and many dams, such as the Hoover Dam, form reservoirs along it. So much water is drawn for drinking water throughout the West and irrigation in California that in some years, water from the Colorado no longer reaches the Gulf of California. The Columbia River, the largest river in volume flowing into the Pacific Ocean from North America, and its tributary, the Snake River, water the Pacific Northwest. The Platte runs through Nebraska and was known for being a mile (2 km) wide but only a half-inch (1 cm) deep. The Rio Grande forms the border between Texas and Mexico before turning due north and splitting New Mexico in half.

Most of the public land held by the U.S. National Forest Service and Bureau of Land Management is in the Western states. Public lands account for 25 to 75 percent of the total land area in these states.[5]

Bureau of Reclamation regions

As a very gross generalization, the climate of the West can be described as overall semiarid; however, parts of the West get extremely high amounts of rain and/or snow, and still other parts are true desert and get less than 10 inches of rain per year. Also, the climate of the West is quite unstable, and areas that are normally wet can be very dry for years and vice versa.

The seasonal temperatures vary greatly throughout the West. Low elevations on the West Coast have warm to very hot summers and get little to no snow. The Desert Southwest has very hot summers and mild winters. While the mountains in the southwest receive generally large amounts of snow. The Inland Northwest has a continental climate of warm to hot summers and cold to bitter cold winters.

Annual rainfall is greater in the eastern portions, gradually tapering off until reaching the Pacific Coast where it again increases. In fact, the greatest annual rainfall in the United States falls in the coastal regions of the Pacific Northwest. Drought is much more common in the West than the rest of the United States. The driest place recorded in the U.S. is Death Valley, California.[6]

Violent thunderstorms occur east of the Rockies. Tornadoes occur every spring on the southern plains, with the most common and most destructive centered on Tornado Alley, which covers eastern portions of the West, (Texas to North Dakota), and all states in between and to the east.

Agriculture varies depending on rainfall, irrigation, soil, elevation, and temperature extremes. The arid regions generally support only livestock grazing, chiefly beef cattle. The wheat belt extends from Texas through the Dakotas, producing most of the wheat and soybeans in the U.S. and exporting more to the rest of the world. Irrigation in the Southwest allows the growing of great quantities of fruits, nuts, and vegetables as well as grain, hay, and flowers. Texas is a major cattle and sheep raising area, as well as the nation's largest producer of cotton. Washington is famous for its apples, and Idaho for its potatoes. California and Arizona are major producers of citrus crops, although growing metropolitan sprawl is absorbing much of this land.

Local state and Government officials started to understand, after several surveys made during the latter part of the 19th century, that only action by the federal government could provide water resources needed to support the development of the West. Starting in 1902, Congress passed a series of acts authorizing the establishment of the United States Bureau of Reclamation to oversee water development projects in seventeen western states.

During the first half of the 20th century, dams and irrigation projects provided water for rapid agricultural growth throughout the West and brought prosperity for several states, where agriculture had previously only been subsistence level. Following World War II, the West's cities experienced an economic and population boom. The population growth, mostly in the Southwest states of New Mexico, Utah, Colorado, Arizona, and Nevada, has strained water and power resources, with water diverted from agricultural uses to major population centers, such as Las Vegas and Los Angeles.

Plains make up most of the eastern half of the West, underlain with sedimentary rock from the Upper Paleozoic, Mesozoic, and Cenozoic eras. The Rocky Mountains expose igneous and metamorphic rock both from the Precambrian and from the Phanerozoic eon. The Inter-mountain States and Pacific Northwest have huge expanses of volcanic rock from the Cenozoic era. Salt flats and salt lakes reveal a time when the great inland seas covered much of what is now the West. The Pacific states are the most geologically active areas in the United States. Earthquakes cause major damage every few years in California. While the Pacific states are the most volcanically active areas, extinct volcanoes and lava flows are found throughout most of the western half of the West.

Facing both the Pacific Ocean and the Mexican border, the West has been shaped by a variety of ethnic groups. Hawaii is the only state in the union in which Asian Americans outnumber white American residents. Asians from many countries have settled in California and other coastal states in several waves of immigration since the 19th century, contributing to the Gold Rush, the building of the transcontinental railroad, agriculture, and more recently, high technology.

The border states—California, Arizona, New Mexico, and Texas—all have large Hispanic populations, and the many Spanish place names attest to their history as former Spanish and Mexican territories. Other southwestern states such as Colorado, Utah, and Nevada have large Hispanic populations as well, with many names places also attest to the history of former Mexican territories. Mexican-Americans have also had a growing population in Northwestern states of Oregon and Washington, as well as the southern state of Oklahoma.

The West also contains much of the Native American population in the U.S., particularly in the large reservations in the mountain and desert states.

Hollywood is a well-known area of Los Angeles and the symbolic center of the American film industry.

The largest concentrations for black Americans in the West can be found in Los Angeles, Oakland, Sacramento, San Francisco, Las Vegas, Denver, Colorado Springs and parts of Arizona.

Alaska—the northernmost state in the Union—is a vast land of few people, many of them native, and of great stretches of wilderness, protected in national parks and wildlife refuges. Hawaii's location makes it a major gateway between the U.S. and Asia, as well as a center for tourism.

In the Pacific Coast states, the wide areas filled with small towns, farms, and forests are supplemented by a few big port cities which have evolved into world centers for the media and technology industries. Now the second largest city in the nation, Los Angeles is best known as the home of the Hollywoodfilm industry; the area around Los Angeles also was a major center for the aerospace industry by World War II, though Boeing, located in Washington state would lead the aerospace industry. Fueled by the growth of Los Angeles—as well as the San Francisco Bay area, including Silicon Valley—the center of America's high tech industry-California has become the most populous of all the states. Oregon and Washington have also seen rapid growth with the rise of Boeing and Microsoft along with agriculture and resource based industries. The desert and mountain states have relatively low population densities, and developed as ranching and mining areas which are only recently becoming urbanized. Most of them have highly individualistic cultures, and have worked to balance the interests of urban development, recreation, and the environment.

Major settlement of the western territories by migrants from the states in the east developed rapidly in the 1840s, largely through the Oregon Trail and the California Gold Rush of 1849; California experienced such a rapid growth in a few short months that it was admitted to statehood in 1850 without the normal transitory phase of becoming an official territory. The largest migration in American history occurred in the 1840s as the Latter Day Saints left the Midwest for the safety of the West. Both Omaha, Nebraska and St. Louis, Missouri laid claim to the title, "Gateway to the West" during this period. Omaha, home to the Union Pacific Railroad and the Mormon Trail, made its fortunes on outfitting settlers; St. Louis built itself upon the vast fur trade in the West before its settlement.

The 1850s were marked by political controversies which were part of the national issues leading to the Civil War, though California had been established as a non-slave state in the Compromise of 1850; California played little role in the war itself due to its geographic distance from major campaigns. In the aftermath of the Civil War, many former Confederate partisans migrated to California during the end of the Reconstruction period.

The history of the American West in the late 19th and early 20th centuries has acquired a cultural mythos in the literature and cinema of the United States. The image of the cowboy, the homesteader and westward expansion took real events and transmuted them into a myth of the west which has influenced American culture since at least the 1920s.

Writers as diverse as Bret Harte and Zane Grey celebrated or derided cowboy culture, while artists such as Frederic Remington created western art as a method of recording the expansion into the west. The American cinema, in particular, created the genre of the western movie, which, in many cases, use the West as a metaphor for the virtue of self-reliance and an American ethos. The contrast between the romanticism of culture about the West and the actuality of the history of the westward expansion has been a theme of late 20th and early 21st century scholarship about the West. Cowboy culture has become embedded in the American experience as a common cultural touchstone, and modern forms as diverse as country and western music and the works of artist Georgia O'Keeffe have celebrated the supposed sense of isolation and independence of spirit inspired by the unpopulated and relatively harsh climate of the region.

As a result of the various periods of rapid growth, many new residents were immigrants who were seeking to make a new start after previous histories of either personal failure or hostilities developed in their previous communities. With these and other migrants who harbored more commercial goals in the opening country, the area developed a strong ethos of self-determinism and individual freedom, as communities were created whose residents shared no prior connection or common set of ideals and allegiances. The open land of the region allowed residents to live at a much greater distance from neighbors than had been possible in eastern cities, and an ethic of tolerance for the different values and goals of other residents developed. California's state constitutions (in both 1849 and 1879) were largely drafted by groups which sought a strong emphasis on individual property rights and personal freedom, arguably at the expense of ideals tending toward civic community.

By 1890, the frontier was gone.[7] The advent of the automobile enabled the average American to tour the West. Western businessmen promoted U.S. Route 66 as a means to bring tourism and industry to the West. In the 1950s, representatives from all the western states built the Cowboy Hall of Fame and Western Heritage Center to showcase western culture and greet travelers from the East. During the latter half of the 20th century, several transcontinental interstate highways crossed the West bringing more trade and tourists from the East. In the news, reports spoke of oil boom towns in Texas and Oklahoma rivaling the old mining camps for their lawlessness, of the Dust Bowl forcing children of the original homesteaders even further west. The movies replaced the dime novel as the chief entertainment source featuring western fiction.

Although there has been segregation, along with accusations of racial profiling and police brutality towards minorities due to issues such as illegal immigration and a racial shift in neighborhood demographics, sometimes leading to racially based riots, the West has a continuing reputation for being open-minded and for being one of the most racially progressive areas in the United States.

The prevalence of libertarian political attitudes is widespread. For example, the majority of Western states have legalized medicinal marijuana (all but Utah, and Wyoming) and some forms of gambling (except Utah); Oregon and Washington have legalized physician-assisted suicide; Most rural counties in Nevada allow licensed brothels. There is less resistance to the legal recognition of same-sex unions: California, Hawaii, Nevada, Oregon, and Washington recognize them.

The West Coast leans toward the Democratic Party. San Francisco's two main political parties are the Green Party and the Democratic Party. Seattle has historically been a center of radical left-wing politics. Both the Democratic leaders of the Congress are from the region: House Minority Leader Nancy Pelosi of California and Senate Majority Leader Harry Reid of Nevada.

Interior areas are more Republican, with Alaska, Arizona, Idaho, Utah, and Wyoming being Republican strongholds, and Colorado, Montana, Nevada, and New Mexico being swing states. The state of Arizona has been won by the Republican presidential candidate in every election except one since 1948, while the states of Idaho, Utah, and Wyoming have been won by the Republican presidential candidate in every election since 1964.

As the fastest-growing demographic group, Latinos are hotly contested by both parties. Immigration is an important political issue for this group. Backlash against illegal immigration led to the passage of California Proposition 187 in 1994, a ballot initiative which would have denied many public services to illegal immigrants. Association of this proposal with the California Republicans, especially incumbent governor Pete Wilson, drove many Hispanic voters to the Democrats.[8]

^Frederick Jackson Turner, The Significance of the Frontier in American History, 1920, ISBN 0486291677, Ch.1: "In a recent bulletin of the Superintendent of the Census for 1890 appear these significant words: "Up to and including 1880 the country had a frontier of settlement, but at present the unsettled area has been so broken into by isolated bodies of settlement that there can hardly be said to be a frontier line. In the discussion of its extent, its westward movement, etc., it can not, therefore, any longer have a place in the census reports." On-line version of the book